This invention relates to a rolling bearing apparatus, and more particularly to a rolling bearing apparatus suited for use in a machine tool (such as a high-speed rotation spindle) and a turbo-molecular pump.
One conventional structure for supplying lubricant to a bearing is described at page 259 of Practical Handbook of Rolling Bearings (First Edition) (Industrial Research Association).
This lubricant supplying structure includes a rotor (rotating member) capable of rotating at high speed, and an oil reservoir, and the rotor has a distal end portion of a conical shape. The distal end portion of the rotor extends generally parallel to a vertical direction in such a manner that a larger-diameter-side portion of the distal end portion is located at the upper side in the vertical direction, while a smaller-diameter-side portion of the distal end portion is immersed in lubricant held in the oil reservoir.
In this lubricant supplying structure, under the influence of a centrifugal force produced in accordance with the high-speed rotation of the rotor, the lubricant in the oil reservoir is moved to an annular groove formed in the larger-diameter-side portion (disposed at the upper side in the vertical direction) of the rotor, and is further supplied from this annular groove to the bearing.
In the above conventional lubricant supplying structure, in the case where the amount of the lubricant is reduced as much as possible for the purpose of remarkably reducing a running torque, the lubricant can not be sufficiently supplied to the interior of the bearing, and this invites a problem that rolling element guide surfaces of a cage of the bearing and other portions of the bearing fail to be properly lubricated.